const fs = require('fs')
const path = require('path')
const os = require('os')
const { execSync } = require('child_process')
const AdmZip = require('adm-zip')
const { downloadWithRedirects } = require('./download')

// Base URL for downloading bun binaries
const BUN_RELEASE_BASE_URL = 'https://github.com/oven-sh/bun/releases/download'
const DEFAULT_BUN_VERSION = '1.2.5' // Default fallback version

// Mapping of platform+arch to binary package name
const BUN_PACKAGES = {
    'darwin-arm64': 'bun-darwin-aarch64.zip',
    'darwin-x64': 'bun-darwin-x64.zip',
    'win32-x64': 'bun-windows-x64.zip',
    'win32-x64-baseline': 'bun-windows-x64-baseline.zip',
    'linux-x64': 'bun-linux-x64.zip',
    'linux-x64-baseline': 'bun-linux-x64-baseline.zip',
    'linux-arm64': 'bun-linux-aarch64.zip',
    // MUSL variants
    'linux-musl-x64': 'bun-linux-x64-musl.zip',
    'linux-musl-x64-baseline': 'bun-linux-x64-musl-baseline.zip',
    'linux-musl-arm64': 'bun-linux-aarch64-musl.zip'
}

/**
 * Downloads and extracts the bun binary for the specified platform and architecture
 * @param {string} platform Platform to download for (e.g., 'darwin', 'win32', 'linux')
 * @param {string} arch Architecture to download for (e.g., 'x64', 'arm64')
 * @param {string} version Version of bun to download
 * @param {boolean} isMusl Whether to use MUSL variant for Linux
 * @param {boolean} isBaseline Whether to use baseline variant
 */
async function downloadBunBinary(platform, arch, version = DEFAULT_BUN_VERSION, isMusl = false, isBaseline = false) {
    let platformKey = isMusl ? `${platform}-musl-${arch}` : `${platform}-${arch}`
    if (isBaseline) {
        platformKey += '-baseline'
    }
    const packageName = BUN_PACKAGES[platformKey]

    if (!packageName) {
        console.error(`No binary available for ${platformKey}`)
        return false
    }

    // Create output directory structure
    const binDir = path.join(os.homedir(), '.we0', 'bin')
    // Ensure directories exist
    fs.mkdirSync(binDir, { recursive: true })

    // Download URL for the specific binary
    const downloadUrl = `${BUN_RELEASE_BASE_URL}/bun-v${version}/${packageName}`
    const tempdir = os.tmpdir()
    // Create a temporary file for the downloaded binary
    const tempFilename = path.join(tempdir, packageName)

    try {
        console.log(`Downloading bun ${version} for ${platformKey}...`)
        console.log(`URL: ${downloadUrl}`)

        // Use the new download function
        await downloadWithRedirects(downloadUrl, tempFilename)

        // Extract the zip file using adm-zip
        console.log(`Extracting ${packageName} to ${binDir}...`)
        const zip = new AdmZip(tempFilename)
        zip.extractAllTo(tempdir, true)

        // Move files using Node.js fs
        const sourceDir = path.join(tempdir, packageName.split('.')[0])
        const files = fs.readdirSync(sourceDir)

        for (const file of files) {
            const sourcePath = path.join(sourceDir, file)
            const destPath = path.join(binDir, file)

            fs.copyFileSync(sourcePath, destPath)
            fs.unlinkSync(sourcePath)

            // Set executable permissions for non-Windows platforms
            if (platform !== 'win32') {
                try {
                    // 755 permission: rwxr-xr-x
                    fs.chmodSync(destPath, '755')
                } catch (error) {
                    console.warn(`Warning: Failed to set executable permissions: ${error.message}`)
                }
            }
        }

        // Clean up
        fs.unlinkSync(tempFilename)
        fs.rmSync(sourceDir, { recursive: true })

        console.log(`Successfully installed bun ${version} for ${platformKey}`)
        return true
    } catch (error) {
        console.error(`Error installing bun for ${platformKey}: ${error.message}`)
        // Clean up temporary file if it exists
        if (fs.existsSync(tempFilename)) {
            fs.unlinkSync(tempFilename)
        }

        // Check if binDir is empty and remove it if so
        try {
            const files = fs.readdirSync(binDir)
            if (files.length === 0) {
                fs.rmSync(binDir, { recursive: true })
                console.log(`Removed empty directory: ${binDir}`)
            }
        } catch (cleanupError) {
            console.warn(`Warning: Failed to clean up directory: ${cleanupError.message}`)
        }

        return false
    }
}

/**
 * Detects current platform and architecture
 */
function detectPlatformAndArch() {
    const platform = os.platform()
    const arch = os.arch()
    const isMusl = platform === 'linux' && detectIsMusl()
    const isBaseline = platform === 'win32'

    return { platform, arch, isMusl, isBaseline }
}

/**
 * Attempts to detect if running on MUSL libc
 */
function detectIsMusl() {
    try {
        // Simple check for Alpine Linux which uses MUSL
        const output = execSync('cat /etc/os-release').toString()
        return output.toLowerCase().includes('alpine')
    } catch (error) {
        return false
    }
}

/**
 * Main function to install bun
 */
async function installBun() {
    // Get the latest version if no specific version is provided
    const version = DEFAULT_BUN_VERSION
    console.log(`Using bun version: ${version}`)

    const { platform, arch, isMusl, isBaseline } = detectPlatformAndArch()

    console.log(
        `Installing bun ${version} for ${platform}-${arch}${isMusl ? ' (MUSL)' : ''}${isBaseline ? ' (baseline)' : ''}...`
    )

    await downloadBunBinary(platform, arch, version, isMusl, isBaseline)
}

// Run the installation
installBun()
    .then(() => {
        console.log('Installation successful')
        process.exit(0)
    })
    .catch((error) => {
        console.error('Installation failed:', error)
        process.exit(1)
    })